Batteries based on lithium (Li), such as lithium-ion batteries, are attractive due to their high energy density compared to other commercial batteries (e.g., alkaline batteries). Li-ion batteries are used commercially in computers, cell phones, and related devices. Li-ion batteries have potential for use in electric vehicle and hybrid-electric vehicle applications.
It is desirable to maintain high battery capacity while being electrochemically reversible. Appropriate nanomaterials enable fast reaction kinetics due to reduced diffusion distances. Higher power output and faster charging times can result when lithium ions are able to diffuse into and out of the active battery material quickly. Nanometer-sized battery materials have multiple challenges for implementation, however.
When batteries are cycled through charging and discharging reactions, agglomeration can lead to bulk structures, derived from the nanomaterials, within the battery. Bulk structures have relatively long diffusion distances which results in slower ion diffusion during battery operation, and thus lower power output. Additionally, bulk structures can readily lose electrical contact with the electrode due to stress cracking as ions diffuse into and out of them, thereby reducing battery capacity.
Also, it is difficult to form electrical connections to nanomaterials that are present in high density. Nanomaterials may be deposited on a two-dimensional surface, but this causes a low density of active battery material. If nanomaterials are dispersed with a conductive material such as carbon black, a significant portion of nanoparticles will be in poor electrical contact with the electrode, which will cause capacity loss.
The current state of the art is deficient with respect to the utilization of nanometer-sized battery materials. What is needed is a method to control the dimensions associated with the active battery material, such as through the presence of a scaffold material. It would be particularly desirable to employ a conductive and chemically stable scaffold suitable for infiltrating a liquid precursor of one or more desired active battery materials, such as oxides and phosphates.